Pressure-sensitive adhesives comprising an acrylic polymer, a natural rubber, etc., as the main component have been widely utilized in various fields and recently, for improving the simplicity of workings and for improving safety and hygiene, an adhesive treatment is almost carried out using an adhesive sheet or tape in place of a liquid-type adhesive.
However, an acrylic pressure-sensitive adhesive which does not contain a tackifier is slightly poor in the adhesive property to materials such as plastics, etc., and on the other hand, a rubber-based pressure-sensitive adhesive and an acrylic pressure-sensitive adhesive containing a tackifier may have a relatively good adhesive property to plastics, etc., but has a problem that such adhesives are poor in the durability for a long period of time and the creep characteristics.